Method of attaching a metal base plate to a plastic container



Jan. 14, 1969 R. HIMELSBAUGHQ 3,421,467

METHOD OF ATTACHING A METAL BASE PLATE TO A PLASTIC CONTAINER Filed Oct.14, 1963 INVENTOR. RUDOLPH HIMELSBAUGH aQ/QQM 7 m ATTYS.

United States Patent Ofifice 3,421,467 Patented Jan. 14, 1969 3,421,467METHOD OF ATTACHING A METAL BASE PLATE TO A PLASTIC CONTAINER RudolphHimelsbaugh, North Royalton, Ohio, assignor to Thermal Engineering &Design Company, Akron, Ohio, a corporation of Ohio Filed Oct. 14, 1963,Ser. No. 316,049 US. Cl. 113121 Int. Cl. B2111 51/38 9 Claims ABSTRACTOF THE DISCLOSURE The present invention relates to containers, andespecially to a combined metal and plastic article or container and to amethod of attaching a metal base plate or section to'a wall of a plasticcontainer to form a wafer-tight article.

Heretofore there have been various efforts made to provide some type ofa container, at least primarily made from a plastic material, which isadaped to have heat supplied thereto for heating the contents of thecontainer. A percolator is one example of such type of a container andin this instance it is necessary to at.ach a metal base plate to thecontainer to close an opening formed in the bottom portion of thecontainer in order to obtain an operative structure. Containers of thistype have been proposed heretofore for use as coffee percolators, forexample, although any type of a cooking utensil, or water heating memberis contemplated to be made by the method of the present invention.

Specifically, with plastic containers and metal bottoms, or basesections therefor, the different coefficients of expansion andcontraction of the materials involved have made it difficult to securethem together by a watertight joint. Also, some of such members asproposed heretofore have had the joint, or connection between theplastic and the metal formed on a generally vertically extending axis,at least substantially the same axis on which the separating forcesbetween the plastic container and the bottom plate are applied wherebyit is difiicult to obtain a water-tight, permanent connection between awall of the plastic article or container and the metal bottom plate orsection.

These water-tight containers or articles are subjected to severestresses in use. For example, the articles may be heated to relativelyhigh temperatures with nothing in the plastic container and thisproduces appreciable thermal distortion of the metal bottom plate and/orthe container and/or the connection therebetween. In ordinary use, thecontainer is repeatedly put through heating and cooling cycles coveringa range of about 100, or more. All of such heating and cooling actionson the container naturally stress it and the components thereof severelyand particularly stress the connection formed between the plastic andmetal sections thereof.

The general object of the present invention is to provide a novel andimproved method of obtaining a watertight article from a plasticcontainer section having an end wall defining a bottom opening thereinand a metal bottom or base plate for the plastic container section orportion.

Another object of the invention is to use the distortion, resiliency andshaping of a radially inner wall of a groove in a metal plate to aid insecuring a container wall in the groove in the metal plate by distortionof a radially outer wall of the groove towards the inner wall of thegroove.

Another object of the invention is to provide a novel and improvedwater-tight article that is made from a plastic container body having abottom opening therein and a metal bottom plate where the plasticcontainer body and the metal base plate have mechanically interlockedwalls provided thereon for securing such members together by a permanentwater-tight connection.

A further object of the invention is to provide a relativelyuncomplicated, but positive method for securing the walls of a groove ina metal bottom plate to a protruding end wall of a plastic article forlocking engagement between such walls, and yet another object is to usethe resiliency in metal plate walls to seal them to a plastic wallreceived between a pair of metal walls.

The foregoing and other objects and advantages of the invention will bemade more apparent as the specification proceeds.

Attention now is particularly directed to the accompanying drawingswhich show one currently preferred embodiment of the principles of themethod of the present invention, and where:

FIG. 1 shows an elevation, partly in vertical section, of a containerand a metal bottom plate therefor showing the parts in exploded, orunassembled relationship;

FIG. 2 is a fragmentary enlarged vertical elevation showing the firststep in the engagement of a downwardly extending end wall of the plasliccontainer with the upwardly facing or open groove in the bottom plate;

FIG. 3 is a fragmentary vertical section, like FIG. 2, showing therelation of the parts after the first shaping operation;

FIG. 4 is a fragmentary vertical section, like FIG. 2, but showing theshaping operation on the outer wall of the groove in the bottom plate;

FIG. 5 is a fragmentary vertical section, like FIG. 2, of the connectionformed between the container and the bottom plate, after engagement isformed. therebetween;

FIG. 6 shows a fragmentary vertical section of a modified articleproduced by the method of the invention but where a different type of aconnection is provided between the bottom member and the containersection, or body;

FIG. 7 is a fragmentary vertical section of a further type of containerassembly of the invention; and

FIG. 8 is another fragmentary vertical section of a container providedby the invention.

The present invention, generally speaking, relates to a method ofsecuring a plastic container to a metal bottom plate or member thereforwhich container and bottom member are secured together by, in oneembodiment of the invention, an interlocked mechanical joint providedbetween a downwardly extending end wall on the container received in adownwardly extending but upwardly open groove in the bottom plate formedby vertically extending groove walls, and where the method comprises, inone embodiment, the steps of forcing the inner wall of the grooveradially outwardly primarily at the upper end thereof to incline suchinner wall outwardly, and rolling the outer wall of the groove radiallyinwardly primarily at the upper margin thereof to incline such wall toextend inwardly of the groove while supporting the inner wall primarilyadjacent the lower end thereof to provide a mechanical interlock betweenthe end wall and the groove walls of the base plate.

Attention now is particularly directed to the details of this structureshown in the drawings and the method steps of the invention shown in thedrawings. In the method of the invention, some type of a plasticcontainer or body, indicated as a whole by the numeral 1, is adapted tobe secured to a metal bottom plate 2 therefor to form an Article A.Normally this plastic container 1 can be made from any high temperatureor heat resistant plastic, such as polypropylene, which plastic can becompounded in a conventional manner so that it will only have a meltingor fusing temperature of about 330 F. Such container 1 has a downwardlyextending end wall 3 fonmed thereon, which wall may be formed in thebottom of the container 1 and with the end Wall 3, for example, beingannular, and usually extending vertically. Such end wall 3 is adapted tobe received in an upwardly open groove 4 provided in the metal bottomplate 2 by a radially inner Wall 5 and a radially outer wall 6 with suchgroove walls usually being parallel and complementary in size and shapeto the container Wall 3 to receive it snugly therein. The metal bottomplate 2 may be adapted to position suitable means, such as anyconventional or other electric heater member (not shown) thereon withthe container 1, or such metal bottom plate may just be a plate forforming a liquid containing compartment with the container 1, asdesired.

In order to secure the bottom plate 2 to the container 1, initially theinner wall 5 has a forming tool, such as a roll 7, brought intoengagement therewith. Such roll 7 has a contour and is so positionedwith relation to the vertical that the positioning axis, or shaft 8, forexample, of the roll 7 is inclined at a slight acute angle, such as 5,to the horizontal when the surfaces of the roll 7 are substantiallycylindrical for good rolling action. The edges of the roll are radiusedto avoid any sharp rolling edge engaging the Walls of the groove orchannel 4. In all events, the surfaces of the roll 7 are so formed as toengage the inner wall 5 primarily at the upper end thereof and, by aprogressive movement of the roll 7, for example, the inner wall 5 isultimately shaped to substantially the position shown in FIG. 3, or sothat the upper end is distorted radially outwardly. As shown, the innerWall extends at an acute angle, such as about 5, radially outwardly andupwardly of the bottom plate to form a mechanical engagement with theend wall 3 at least at the upper portion thereof where it connects tothe remainder of the container 1.

In order to obtain a further mechanical interlock with and a better bondof the groove 4 and its walls with the end wall 3, a second formingmeans, such as a suitably driven roll 9 is provided and is positioned ona suitable support shaft 10. It is an important feature of the inventionthat this roll 9 is so positioned, or shaped as to engage the upperportion of the outer wall 6 and to progressively roll or move at leastsuch upper end of the outer wall axially inwardly of the bottom plate 2by movement of the roll 9 relative to the outer wall 6. Preferably thesupport shaft '10 so positions the roll 9, or the roll is contoured sothat such outer wall can be shaped to extend inwardly of the bottomplate at an angle of approximately 12, for example, with relation to thevertical and form a reduced distance between the adjacent surfaces ofthe walls 5 and 6 of the groove 4 to provide a pinching action on theplastic end wall 3. Normally the plastic forming such Wall is of arelatively hard, but yet plastic or yieldable composition wherebysufficient pressures applied thereto will cause some cold flow of theplastic to adjust itself to the space provided. The outer 'wall 6usually is deflected to a greater degree or angle than the inner wall 5.

It is an important feature of the invention that the inner Wall 5 issupported, or reenforced while the roll 9 is brought into engagementwith the outer wall 6. This reenforcement provided for the inner wall 5may be in the form of a support member, indicated at 11 in FIG. 4, andwhich support has a flat front edge surface 11a that engages primarilywith the inner wall 5 only adjacent the lower end thereof. By thisparticular type of rolling or shaping action provided by the invention,the upper portion of the inner wall 5, indicated at 5a, due to itscontour and prior working, 'will have a resilient resistance set uptherein to axial inward movement thereof by the pressures applied to theouter wall 6 by the roll 9. Possibly this section 5a of the inner wallmay be forced radially inwardly, or be reshaped to a vertical positionby the action of the roll 9. So as to avoid any vertical deformation ofthe center portion of the bottomplate 2, a support member 12 isassociated with the upper face of the bottom plate to prevent distortionthereof during the rolling action by the roll 9. The bottom plate mayalso be reenforced during the operative action of the roll 7, ifdesired.

FIG. 5 show show the upper portions 5a and 6a of the Walls 5 and 6,respectively, will provide a good mechanical interlock between the wallsof the groove 4 and the end 'wall 3 of the plastic container wherebyeven though axially directed separating forces are applied to theconnection between the bottom plate and the container wall, still aneffective, tight, bonded interlock will be obtained and maintainedtherebetween to provide a permanent water-tight, or liquid-tightconnection therebetween. Such connection is aided, usually, by some coldflow of the plastic material forming the container wall. The actualconnection of the groove 4 and end wall 3 may be in a verticaldinection, or the slightly inclined with relation to such direction.

FIG. 6 of the drawing is of interest because a modified metal bottomplate or member 2a is secured to a container 1a. In this instance, themetal bottom plate has an upwardly extending section 20 formed thereonwith an upwardly open groove 4a formed therein by means of an outer wall21 and an inner wall 22. In this instance, the inner wall 22 has twothicknesses of the bottom plate provided therein, as indicated at 23 and24, and with the adjacent walls of these portions 23 and 24 of the innerwall being directly abutted against each other by being bent into tightcontact with each other in their original forming operation. Preferablythis inner wall 22 is radially offset from the radially outer wall 21,which wall 21 lies in the normal contour of the upwardly extendingsection 20 of the bottom plate 2a.

The rolling or shaping actions provided for this container 1a and bottomplate or member 2a would be exactly the same in principle as thoseoutlined hereinbefore. Any suitable reenforcing, rolling, or formingmembers can be introduced through the open tops of the containers 1 and1a, or through any openings that may be provided in the metal bottomplates 2, or metal bottom members 2a of the assemblies to be associatedWithin the forming or shaping tools applied to the outside of theplates.

Usually the metal bottom plates 2 and 2a are made from uniform thicknesssheets of some material that is a poor heat conductor, such as stainlesssteel, but it is Within the scope of the invention to form these membersfrom other conventional materials, such as aluminum. The containers madeby the invenion are particularly desirable when the bottoms therein areformed from stainless steel as this prevents transmission of hightemperatures from the electric heater means secured to the centers ofthe bottom plate 2, when used in percolators, out to the radially outermargins of the bottom plates or members so that the plastic in thecontainer assembly is not severely heat stressed by normal use thereof.

It will be realized that the rolls 7 and 9 shown in the drawings areindicated as having a smaller effective rolling width than the height ofthe flanges or walls 5 and 6 on which the rolling action of theinvention is effected.

Hence, there will be some relatively vertical movement of the roll alongthese walls for the desired compressing action on the plastic containerwall. However, in some instances, it may be desirable to provide just alocalized rolling action to provide more or less of a bead or rib on theinner wall 5, for example, or on the outer wall 6 and still a verydesirable securing action will be obtained by localized pressure actionon the container wall 3.

In the modification of the invention shown in FIG. 7, a metal base plate212 is provided that has an initially outwardly inclined groove 4bformed therein. Such groove 4b would have one wall 6b thereof of a shapeas indicated in dotted lines 'in FIG. 7 and, after engaging thecontainer, the wall 6b would be suitably worked or forced over intoengagement with a horizontally extending flange 30 on a container 2badjacent an opening in the bottom thereof. This shaping of the wall 6bcan be done by a roll, like the roll 7, brought into engagement with thewall 6b. A wall 5b forming the inner wall of the U-shaped groove 4bprovided on the metal base plate 2b is preferably initially shaped toextend upwardly at an angle to the horizontal of about 5". Such rib orgroove 4b, when permanently positioned, is horizontally extending and isfacing radially inwardly of the container assembly to engage the flangeor wall 30. The wall 5b hence provides a resilient resistance todeformation when the wall 6b is brought into final engagement with thecontainer wall 30. Itwill be realized that the wall 5b can be suitablyreenforced when the localized rolling action is performed on the otherwall of the groove.

In the embodiment of the invention shown in FIG. 8, a bottom plate has,in effect, a radially outwardly facing horizontally directed groove 4cformed integrally therewith. Suitably positioned means can be inserted,as for example through an aperture provided in the center portion of thebottom plate 20 and from the top of a container 10, to provide a desiredrolling and support action on the opposed walls of this groove 4c, asone or both of such groove walls are forced into engagement with ahorizontally extending wall, or flange 41 formed on the container 10adjacent a bottom opening therein. Initially an upper wall 6c of thegroove 40 would be upwardly directed and be forced over to the positionshown after the container and the bottom plate are associated forpermanent assembly thereof. A wall 50 of the groove may abut on anadjacent portion of the bottom plate and be worked to an inclination tothe horizontal of about 5 before the bottom plate and container areassembled.

While it is not the preferred practice of the invention, in someinstances it is possible to obtain satisfactory sealed connectionbetween the container wall 3- and the bottom plate of the invention byeither a rolling action, preferably localized, performed solely on theinner wall 5 or on the outer wall 6, as desired, but the preferredpractice of the invention utilizes a rolling action on both of suchwalls, as described hereinbefore in more detail.

The term plastic in the present application is used in its normalcommercial sense to refer to a material which has some cold flow underpressure, which has some flexibility, and which is not brittle likeglass. Plastic generally refers to synthetic or semi-synthetic organicsubstances made by polymerization or condensation, or are derived from anatural material by chemical action and which can be molded, cast,extruded, drawn, or laminated under various conditions. The plasticmaterial may either be a thermosetting or a thermoplastic substancewithin the limits outlined hereinabove, and can be readily made ofattractive color and design. Or, combinations of thermosetting andthermoplastic materials by lamination or otherwise that permitssubstantial but resilient pressures to be transmitted thereby can beused in making the container 1 or the like.

When desired, a suitable adhesive could be used to aid in bonding themetal plates to the plastic containers. Such adhesive action may includeheating the metal plate,

when a heat softening plastic is used, at some stage in the attachingprocess.

It can be said that the invention relates to the deforming of at least aportion of a first wall of a groove in a metal plate in one directionand then deforming the other wall of the groove in the oppositedirection but towards the first wall. Force is transmitted through theslightly resilient plastic material forming the wall positioned in thegroove. The first metal wall has a spring resistance to the deformationthereof by the force applied to the other wall to aid in obtaining agood permanent liquid tight bond in the container.

Obviously, the size and shapes of the actual rolls of forming members 7and 9 used in the apparatus of the invention may be varied, but with theshaping actions obtained being those described herein. Such shapingactions on the walls 5 and 6 may provide a rib or ribs thereonprotruding towards the opposite wall by a localized rolling action. Alocalized rib x is shown in FIG. 8. Only the walls 6b and 60 would needto be rolled after assembly of the containers and bottom plates in FIGS.7 and 8.

Any suitable base, or support means may be attached to the containers ofthe invention in known manners. Suitable electric controls also can beprovided and be connected to the electric heaters, when used, tocomplete the small, electric appliances.

By the invention, pairs of continuous, spaced walls of a metal disc ormember are brought into engagement with a plastic container adjacent anopening therein, which walls may extend either substantially vertically,or hori zontally. Thus it is believed that the objects of the inventionhave been achieved.

While several complete embodiments of the invention have been disclosedherein, it will be appreciated that modification of these particularembodiments of the invention may be resorted to without departing fromthe scope of the invention as defined in the appended claims.

What is claimed is:

1. A method of securing a plastic container and a metal bottom platetherefor together to provide a watertight article, which methodcomprises the steps of forming a container having an annular downwardlyextending end wall defining an opening in the container bottom,

providing a metal base plate for the container, which base plate has anannular downwardly extending upwardly open groove therein for receipt ofsaid end wall,

inserting said end wall into said groove,

rolling the inner wall of said groove radially outwardly by pressureapplied only adjacent the upper end thereof to incline such wallupwardly and outwardly, and

rolling the outer wall of said groove radially inwardly at the uppermargin thereof by pressure applied only adjacent the upper end of suchouter wall to incline such wall to extend downwardly and outwardly at agreater angle to the vertical than the inner wall while supporting saidinner wall against radially inwardly movement only adjacent the lowerend thereof, to form a mechanical interlock between said end wall andsaid base plate.

2. A method of securing a plastic container and a metal bottom platetherefor together to provide a watertight article, which methodcomprises the steps of forming a container having an annular downwardlyextending end wall defining an opening in the container bottom,

providing a metal base plate for the container, which base plate has anannular downwardly extending upwardly open groove therein for receipt ofsaid end wall,

forcing said end wall down into said groove,

forcing the inner wall of said groove radially outwardly at only anupper end section thereof to move such wall section outwardly, and

forcing the outer wall of said groove radially inwardly only at theupper end section thereof to move such wall section to extend inwardlyto form a mechanical interlock between said end wall and the walls ofsaid groove in said base plate.

3. A method of securing a plastic container and a metal bottom platetherefor together by an interlocked joint between a downwardly extendingend wall in the container positioned in a downwardly extending upwardlyopen groove in the bottom plate formed by vertically extending radiallyinner and outer groove walls to provide a water-tight article, whichmethod comprises the steps of forcing the inner wall of said grooveradially outwardly primarily at the upper end thereof to incline suchinner wall upwardly and outwardly,

rolling the outer wall of said groove radially inwardly primarily at theupper margin thereof to incline such Wall to extend downwardly andoutwardly of the groove while supporting said inner wall primarilyadjacent the lower end thereof, to form a mechanical interlock betweensaid end wall and said bottom plate, and

reenforcing the upper surface of said bottom plate adjacent said groovewhile rolling said outer wall.

4. A method of securing a plastic container and a metal bottom sectiontherefor together by an interlocked joint between a downwardly extendingend wall in the container received in an upwardly open groove in thebottom section formed by vertically extending, radially spaced inner andouter groove wall means to provide a water-tight article, which methodcomprises the steps of forcing the inner wall means of said grooveradially outwardly only adjacent the upper end thereof to indent suchinner wall means outwardly,

forcing the outer wall means of said groove radially inwardly onlyadjacent the upper margin thereof and opposed to the indent in the innerwall to dent the outer wall means inwardly of the groove to form amechanical interlock between said end wall and said bottom section, and

reenforcing the upper surface of said bottom section adjacent saidgroove while forcing said outer wall means inwardly.

5. A method of securing a plastic container and a metal bottom sectiontherefor together by an interlocked joint between a downwardly extendingend wall in the container received in an upwardly open groove in thebottom section formed by vertically extending, radially spaced inner andouter groove wall means to provide a water-tight article, which methodcomprises the steps of forcing the inner wall means of said grooveradially outwardly only at the upper end thereof to indent such innerwall means outwardly, and

forcing the outer wall means of said groove radially inwardly only atthe upper margin thereof to indent such wall means inwardly of thegroove to form a mechanical interlock between said end wall and saidbottom section.

6. A method of securing a plastic container and a metal bottom therefortogether by an interlocked joint between a downwardly extending end wallin the container outlining an opening therein and an upwardly opengroove in the bottom formed by vertically extending radially spacedgroove Walls to provide a water-tight article, which method comprisesthe steps of inserting the end wall into said groove,

rolling the inner wall of said groove radially outwardly above the lowerend thereof, and

rolling the outer wall of said groove radially inwardly above the lowermargin thereof to force such wall against said container end wall toform a mechanical interlock between said container end wall and saidgroove walls.

7. A method of securing a plastic container and a metal bottom sectiontherefor together by an interlocked joint between a downwardly extendingend wall in the container received in an upwardly open groove in thebottom section formed by vertically extending, radially spaced inner andouter groove wall means to provide a water tight article, which methodcomprises the steps of forcing the inner wall means of said grooveradially outwardly at the upper end thereof to deflect such wall meansat an angle of about 5 to the vertical, and

forcing the inner wall means of said groove radially inwardly to inclinepart of such wall means inwardly of the groove at a greater angle to thevertical than said inner wall means, said inner wall means resilientlyresisting distortion from forces on said outer wall means.

8. A method of securing a plastic container and a metal bottom platetherefor together by an interlocked joint between a protruding wall inthe container adjacent an opening therein and a generally U-shapedperipheral groove in the bottom plate formed by a pair of substantiallyparallel spaced groove walls to provide a liquidtight article, whichmethod comprises the steps of bringing the container wall and saidgroove into engagement with such container wall between said groovewalls,

rolling one wall of said groove towards the other wall primarilyadjacent the connection of such wall to the plate, and

rolling the other wall of said groove towards the first groove wallprimarily at its upper end to compress said container wall between saidgroove walls.

9. A method of securing a plastic container and a metal bottom platetherefor together by an interlocked joint between a protruding end wallin the container adjacent an opening therein and an open generally-shaped in section peripheral integral groove in the bottom plate formedby spaced inner and outer groove walls to provide a liquid-tightarticle, and where the plastic forming said container will cold flowunder pressure, which method comprises the steps of bringing the endwall and the groove walls into engagement, and

forcing one wall of said groove towards the other groove wall by a forceapplied only to an upper portion of such groove wall to compress thecontainer wall therebetween to cause cold flow of the plastic materialforming such wall, and form a mechanical interlock between saidcontainer end wall and said groove walls.

References Cited UNITED STATES PATENTS 2,188,497 1/1940 Calva 113-120 X2,467,182 4/1949 Beattie l13-l20 X CHARLES W. LANHAM, Primary Examiner.R. D. GREFE, Assistant Examiner.

US. Cl. X.R. 113120

